I think that either board/chipset will be great for a NAS, it just depends on what you want to do later on. If you think that you may want to build a new gaming rig soon, then you may want to consider buying an H77 board for this build, as it offers a lower price, and won't be overclocked.
Or, you could use the board that you have on hand, and wait until Haswell is released, which will require a new board anyway.